Phase Correction - I have the power, should I use it?

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  • sfdoddsy
    Senior Member
    • Sep 2000
    • 496

    Phase Correction - I have the power, should I use it?

    I have the frequency response of my dipoles down very flat in room. So, since I have no life, I thought I might take a look at the mysterious world of phase.

    One of the nifty features of my new dbx Driverack 260 is that it allows one to specify delays for all drivers individually, and also adjust the phase for all the drivers individually.

    Do the poobahs think this is worthwhile?

    And if so, what is the best way to find out exactly what phase issues I may have. I have ETF, TrueRTA and the demo version of SpectraLab to play with.

    This swine awaits your pearls.

    Steve




    Steve's DIY Dipoles
    Steve's OB Journey
  • JonMarsh
    Mad Max Moderator
    • Aug 2000
    • 15213

    #2
    Phase and amplitude response are inextricably linked. Now, if you've got your system dialed in for "flat" response, then you've taken care of the phase response in the crossover region already. Adding delay to specific outputs should only mess things up at this point.

    OTOH, it's not likely that you have zero phase errors, just that the phase errors are the normal ones associated with the crossover filters.

    If you want to explore that, and get a little depressed, get a pulse generator and a scope, and try passing a 10 millisecond or 1 millisecond pulse waveform.

    Then, sit back, relax, have a margarita or a good beer, and be thankful we don't seem to hear the way that test instruments can, or the way that most advocates of TP speakers claim we can.

    BTW, been there, done that, wrote the book, optioned the movie, re TP speakers which will pass a good 1 millsecond or 10 millisecond pulse on axis... in the seventies.

    I personally think that if every thing else is similar (axial response, off axis power response, room interaction, etc., most folks will only hear a subtle difference between a good TP speaker and an equally good, but non TP speaker.

    If you do want TP, forget mult-way dynamic speakers, DSP, etc; stay with the dipole thing, though, and get a pair of these:






    Combine it with a dipole sub array, could be pretty dang awesome....

    If I didn't like building stuff so much, they're what I'd own.


    Best regards,

    Jon




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    Comment

    • Dennis H
      Ultra Senior Member
      • Aug 2002
      • 3791

      #3
      Steve, correct me if I'm wrong but I think you were asking a more basic question than the TP stuff Jon dove into. Assuming you followed SL's lead and tailored the response of the drivers for an LR4 acoustic rolloff at the crossovers, it's easy to optimize the driver delays. Just reverse the wire on the mid (or reverse the mid polarity in the DSP) and look at how deep the notches are at the crossover points. Fiddle with the delays to get the notches as deep as possible.

      Comment

      • sfdoddsy
        Senior Member
        • Sep 2000
        • 496

        #4
        Well, I guess I'll just have to listen to music then.

        What an interesting concept.






        Steve's DIY Dipoles
        Steve's OB Journey

        Comment

        • Davey
          Senior Member
          • Jan 2003
          • 355

          #5
          Steve,

          Check the Behringer DCX2496 setup file that I sent you a few weeks back. It's programmed with driver delays that should be about right for your system.

          Cheers,

          Davey.

          Comment

          • sfdoddsy
            Senior Member
            • Sep 2000
            • 496

            #6
            Thanks again Davey. The delays suggested between mids and tweeter were about what I had, but the bass to the others is a bit longer. I did mine from the middle of the H-baffle figuring that to be the acoustic center with front and rear facing drivers, did you do yours from the rear driver?

            Steve




            Steve's DIY Dipoles
            Steve's OB Journey

            Comment

            • Lex
              Moderator Emeritus
              • Apr 2001
              • 27461

              #7
              Well, I guess I'll just have to listen to music then.
              What an interesting concept.
              Interesting concept? It's every DIYer's worst nightmare! :LOL:

              Lex




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              Comment

              • Dennis H
                Ultra Senior Member
                • Aug 2002
                • 3791

                #8
                Speaking of Soundlab stats, there's an 8 year old pair of A1s on Audiogon for $4K. :E :E :E :E

                Must resist, must resist, must resist........

                PS, Jon, they're located just north of you. "Honey, why don't we drive up to Santa Rosa for some sightseeing?" :rf

                Comment

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